It long has been recognized that the hybridization of plants from differing genetic backgrounds commonly leads to the production of F.sub.1 hybrid plants in the first filial generation that possess an increased vigor or heterosis. Such condition is being widely utilized to make possible greater yields in a number of economically significant crops.
Since the parent plants utilized in the hybridization cross commonly are capable of undergoing both self-pollination and cross-pollination, a reliable means must be provided to ensure the consistent formation and harvest of seeds that upon growth will manifest the desired hybrid vigor. Techniques available to achieve this objective have included the mechanical emasculation of seed parent plants, the utilization of gametocides, the utilization of cytoplasmic male sterility, the utilization of male sterility that is controlled solely by nuclear genes, and self-incompatibility of the sporophytic or gametic types. Also, herbicide tolerance sometimes has been imparted to the seed parent plants so that the pollen parent plants used in the cross-pollination can be destroyed at the appropriate time through the use of a herbicide.
To date self-incompatibility has been utilized in some limited areas for the production of F.sub.1 hybrid plants. For instance, self-incompatibility commonly has been utilized in the past in the hybrid production of vegetable Brassica oleracea plants, such as cabbage, broccoli, Brussels sprouts, and cauliflower. See, also U.S. Pat. No. 5,043,282 entitled "Method of Producing Plant Cell Lines of Plant Hybrids" to Frank Scott-Pearse. In the previously proposed hybridization technology utilizing self-incompatibility, it has been the consistent practice to grow adjoining uniform population of each of the parent plants followed by the selective harvest of the F.sub.1 hybrid seeds that are formed on the seed parent plants. Such selective planting and selective harvest procedures are time consuming and tedious to implement on a reliable basis and further add significantly to the production costs in view of the fact that the F.sub.1 hybrid seeds are formed on only a portion of the planting area. The possibility for error at each step is great and in those instances where an error occurs, the consequences tend to be drastic for the consumer. See, for instance, (1) "Breeding Field Crops" by J. M. Poehlman at Pages 132 to 134, Van Nostrand Reinhold Co. Inc., N.Y. (1987); (2) the Ph.D. dissertation of P. Banks of the University of Guelph, Guelph, Ontario, Canada, entitled "Self-Incompatibility and Rapeseed Breeding" (1988); and (3) the Ph.D. dissertation of J. P. Parker of the University of Guelph, Guelph, Ontario, Canada, entitled "Genetic Studies on Self-Incompatibility as a Pollination Control System in Oilseed Rape (Brassica napus L. ssp. oleifera)" (1994).
Numerous alleles for self-incompatibility in a number of crops have been identified in the past and are already known and available to plant scientists. Others can be located in available source materials using recognized screening techniques of a routine nature that can be carried out without undue experimentation.
It is an object of the present invention to provide an improved hybridization process for the production of a predetermined F.sub.1 hybrid cultivar.
It is an object of the present invention to provide an improved hybridization process for the production of a predetermined F.sub.1 hybrid cultivar that utilizes self-incompatibility as the pollination control mechanism.
It is an object of the present invention to provide an improved hybridization process for the production of a predetermined F.sub.I hybrid cultivar wherein each parent plant is randomly grown in the same planting area, and the resulting harvest is non-selective with respect to each of the parent plants.
It is an object of the present invention to provide an improved hybridization process for the production of a predetermined F.sub.1 hybrid cultivar that is readily amenable for commercial implementation on an economical basis.
It is an object of the present invention to provide an improved hybridization process for the production of a predetermined F.sub.1 plant cultivar wherein the necessary pollination control is readily maintainable.
It is an object of the present invention to provide an improved hybridization process that utilizes self-incompatibility wherein the requisite foundation seed required for the formation of the parent plants can be produced under field growing conditions.
It is an object of the present invention to provide an improved hybridization process that in particularly preferred embodiments is suitable for the production of a predetermined F.sub.1 hybrid cultivar of Brassica napus or Brassica campestris (syn. Brassica rapa L.).
It is another object of the present invention to provide a blend (i.e., a mixture) of seeds that is useful during F.sub.1 hybrid seed production in accordance with the concept of the present invention.
It is a further object of the present invention to provide a field of plants that is useful for F.sub.1 hybrid seed production in accordance with the concept of the present invention.
These and other objects, as well as the scope, nature, and utilization of the claimed invention will be apparent to those skilled in plant science from the following detailed description and appended claims.